From ice-shelf tributary to tidewater glacier: continued rapid recession, acceleration and thinning of Rohss Glacier following the 1995 collapse of the Prince Gustav Ice Shelf, Antarctic Peninsula

We use optical (ASTER and Landsat) and radar (ERS-1 and ERS-2) satellite imagery to document changes in the Prince Gustav Ice Shelf, Antarctic Peninsula, and its tributary glaciers before and after its January 1995 collapse. The satellite image record captures the transition from an ice-shelf glacier system to a tidewater glacial system and the subsequent rapid retreat and inferred 'fatal' negative mass balances that occur as lower glacier elevations lead to higher ablation and tidewater-style calving collapse. Pre-1995 images show that the central ice shelf was fed primarily by Sjogren Glacier flowing from the Antarctic Peninsula and by Rohss Glacier flowing from James Ross Island. Numerous structural discontinuities (rifts and crevasses) and melt ponds were present on the ice shelf before the collapse. After the ice shelf collapsed, Rohss Glacier retreated rapidly, becoming a tidewater glacier in 2002 and receding a total of similar to 15 km between January 2001 and March 2009, losing >70% of its area. Topographic profiles of Rohss Glacier from ASTER-derived digital elevation models show a thinning of up to 150 m, and surface speeds increased up to ninefold (0.1-0.9 m d(-1)) over the same period. The rates of speed increase and elevation loss, however, are not monotonic; both rates slowed between late 2002 and 2005, accelerated in 2006 and slowed again in 2008-09. We conclude that tributary glaciers react to ice-shelf removal by rapid (if discontinuous) recession, and that the response of tidewater glaciers on the Antarctic Peninsula to ice-shelf removal occurs over timescales ranging from sub-annual to decadal.